Riddle

1-What is the easiest way to throw a ball, and have it stop, and completely reverse direction after traveling a short distance?

2-What has roots that nobody sees, and is taller than trees. Up, up it goes, and yet it never grows. What is it?

3-I have many feathers to help me fly. I have a body and head, but I'm not alive. It is your strength which determines how far I go. You can hold me in your hand, but I'm never thrown. What am I?

4-You must keep this thing, its loss will affect your brothers. For once yours is lost, it will soon be lost by others.

thinking...